The Background is too plain. Try and make it more eye-catching like using diffrent types of Brushes or something. The text is plain also and it looks horrible (no offense), but yeah, try something that'll fit the picture. But yeah, don't give up, just keep trying and you'll achieve.

Oh ok, hmm. I used to have Gimp and make signatures but I had to delete it off my computer because it took too much memory which slowed my PC down. I had to wait around 10-20 Minutes just for the f'n PC to load. But anyways, may I suggest you have a look the GIMPTALK Tutorial site? It can help you improve on your Graphic skills. It's a forum, and millions of users of GIMP can help you.